I have a signal that is 0-500mV when low and 600-900mV when high. I'd like to buffer this signal to an open collector output. The output must withstand a maximum of 3.3V be capable of sinking 60uA.
The power for the detection circuit is provided by a (CR2023) battery that ranges form 2V to 3.2V.
The goal is to find a simple, cheap, low power solution. (By low power, I am shooting for on the order of 1's-10's of uA.)
One solution is to use a low power comparitor like the TS881, but this would also require an external voltage reference to compare to, adding complexity, cost, and power usage.
Another solution would be to use a reset voltage detector like the NCP303, but these are expensive and don't seem to come with thresholds lower then 0.9V.
I feel like there should be a way to do this simply with discrete parts. Maybe somehow taking advantage of the pinch voltage threshold on a JFET? Or the bandgap on carefully chosen LED?
Ideas?
Best Answer
A bit more detail about our chip (the one that bigjosh is referring to): Find the latest datasheet here, this link won't change. bristol.ac.uk/voltage-detector
We don't advertise this, but we have different threshold levels, UB20M is 0.6V, UB20L is 0.46V, the former has a current draw of below 10 pA, the latter around 100pA, so with some very high impedance sources, the former will trigger sooner.
We have some videos (a layman's video and some demos) here.